```
$ curl -i -u user:pass https://deposit.softwareheritage.org/1/servicedocument/
HTTP/1.1 503 Service Unavailable
Date: Mon, 11 May 2020 14:03:49 GMT
Server: gunicorn/19.9.0
Content-Type: application/xml
Vary: Accept
Allow: GET, POST, PUT, DELETE, HEAD, OPTIONS
X-Frame-Options: SAMEORIGIN
Content-Length: 311
Via: 1.1 deposit.softwareheritage.org
Access-Control-Allow-Origin: *
X-Varnish: 131684
Age: 0
Via: 1.1 varnish (Varnish/6.1)
Strict-Transport-Security: max-age=15768000;
Connection: keep-alive

<?xml version="1.0" encoding="utf-8"?>
<sword:error xmlns="http://www.w3.org/2005/Atom"
       xmlns:sword="http://purl.org/net/sword/">
    <summary>Database backend maintenance</summary>
    <sword:verboseDescription>Service temporarily unavailable, try again later.</sword:verboseDescription>
</sword:error>
```